With continuous development of information technologies, the development of a DWDM (Dense Wavelength Division Multiplexing, dense wavelength division multiplexing) technology provides an effective way for point-to-point large-capacity transmission of optical fibers. In an all-optical communications network, capacity expansion is implemented on a trunk by using the DWDM technology, and optical information exchange is implemented on a cross-connect node by using an optical add/drop multiplexer (OADM) and an optical cross connect (OXC), and fiber to the home (FTTH) is implemented by using an optical fiber access technology. The OXC and the OADM are core technologies of the all-optical network, and the cores of the OXC and the OADM are an optical switch and an optical switch array, micro-electro-mechanical system (MEMS) optical switches may be classified into 2-dimensional micro-electro-mechanical system (2D-MEMS) optical switches and 3-dimensional micro-electro-mechanical system (3D-MEMS) optical switches. Due to unbalanced insertion losses between paths, a 2D-MEMS optical switch cannot be implemented as a large-scale switch array. Because there is a small difference between distances between ports, a 3D-MEMS optical switch can be implemented as a switch matrix of a very large scale. Therefore, the 3D-MEMS optical switch can implement a large-capacity OXC node, which is applicable to the large-capacity optical switching field.
In a 3D-MEMS, an objective of switching an optical channel is achieved through rotation of a micro-mirror and deflection of an optical channel. Due to factors such as inertia and vibration, the micro-mirror cannot rotate to an optimal position quickly and steadily; as a result, an insertion loss of a 3D-MEMS optical switch cannot reach an optimal status. In the prior art, power detection modules are added to an input port and an output port of an optical fiber, input power is compared with output power, a comparison result is fed back to the micro-mirror, and a close loop feedback mechanism is formed, so as to control the micro-mirror. In this way, the micro-mirror is calibrated to an optimal status, to make the insertion loss of the 3D-MEMS optical switch be the smallest.
For the 3D-MEMS optical switch in the prior art, an optical power detection module and a core optical switch module of the optical switch are separately disposed. As shown in FIG. 1, an optical power detection module of an optical switch is located at an input/output port, each input port is connected to one 1×2 coupler (coupler), and two output ports of the coupler can perform light splitting according to a requirement, such as 5%:95%, 2%:98%, or 10%:90%. A port with a small split ratio is connected to a PD (power detector, power detector), which is configured to detect optical power. The other port with a large split ratio is connected to a core optical switch module. All couplers and PDs of the input ports are disposed in one optical power detection module, and similarly, one optical power detection module is also formed at the output port.
In the prior art, power detection modules are added to an input port and an output port of an optical fiber; and a core optical switch module and an optical power detection module are separately disposed, and both need to be connected to a main control board by using data cables. A length of a data cable limits a communication rate between the optical power detection module and the core optical switch module, and a time for a micro-mirror to stabilize after calibration is prolonged. When a large-scale 3D-MEMS optical switch needs to be implemented, a relatively large quantity of couplers and PDs need to be used, and a volume of the optical power detection module becomes very large, which does not facilitate actual use. Each port uses one coupler and one PD, and as a scale of a 3D-MEMS increases, costs are increased.